Postural instability and the condition of physical frailty in the elderly

Objective: to analyze the relationship between postural instability and the condition and markers of physical frailty of the elderly people in outpatient geriatric and gerontology care. Method: a cross-sectional study with a sample of 381 elderly subjects. Physical frailty was evaluated by the frailty phenotype and postural instability through the Berg Balance Scale. Univariate analyses consisted in Chi-square tests, and multivariate analyses used the Forward Stepwise method, which resulted in a model of physical frailty associated with postural instability. Results: among the participants, 56 (14.7%) were frail, 217 (57%) pre-frail, and 68 (28.3%) non-frail. Pre-frailty (p < 0.001), frailty (p = 0.000), and the markers hand grip strength (p = 0.0008), unintentional weight loss (p = 0.0094), level of physical activity (p = 0.0001), fatigue/exhaustion (p = 0.0001), and gait speed (p = 0.0001) were associated with postural instability. Conclusion: the presence of postural instability determines a greater chance of the elderly being frail or pre-frail. This result favors the planning of gerontological nursing care and strengthens the treatment plan under a specific approach.


Introduction
Frailty is considered a wide-ranging geriatric syndrome due to the high prevalence in the elderly population and the negative impact on the treatment plan of other geriatric syndromes, since frail elderly individuals are at increased risk for developing other disabilities (1) .
Experts on physical frailty define it as a "medical syndrome with multiple causes and contributions, characterized by decreased strength, resistance, and reduced physiological function that increases the vulnerability of individuals and leads to greater dependence and/or death" (2) .
The frailty syndrome in the elderly can be diagnosed according to the frailty phenotype, which consists of the measurement of five biological markers: gait velocity, hand grip strength, unintentional weight loss, level of physical activity, and self-report of fatigue/exhaustion. The elderly with three or more of these markers are considered frail; those with one or two criteria are in the pre-frail stage, and those who do not present any of the mentioned components are considered non-frail (3) .
Geriatric syndromes are multifactorial conditions that involve the interaction of stressing situations and risk factors that cause damage to the systems (4) . When associated with frailty, they represent a syndromic picture of a multisystemic nature (3) , which results in difficulty to restore functions and loss of independence (5) .
This progression induces the decline of physiological functions until death (3) .
Recognized as one of the geriatric syndromes (6) , postural instability can be defined as the inability to integrate sensory information and determine body oscillations in the upright position while maintaining balance (7) . Although frequently used by researchers, there is no standardized use for the term postural balance, and for this reason, it is commonly used in association with other terms (8) .
"Balance involves the reception and integration of sensory stimuli, and the planning and execution of movements to control the center of gravity on the base support, by the postural control system that integrates information from the vestibular and somatosensory system and visual receptors" (9)(10) .
During the aging process, these systems may become incapable of performing such functions. This leads to physical decline in the elderly and consequent impairment in the performance of daily tasks (11) . In a systematic review of the literature, researchers analyzed the predictive value of disabilities in activities of daily living (ADL) in the elderly and concluded that those with balance deficits were at greater risk of developing disabilities in ADL (12) . This functional limitation decreases postural control and predisposes the elderly to falls (13) .
According to the American Geriatrics Society (AGS) and the British Geriatrics Society (14) , falls are associated with restricted mobility, fractures, depression, functional disability, loss of independence and autonomy, institutionalization, decline in quality of life, socioeconomic implications, and over-burden to health systems.
Evidence shows that postural instability is related to frailty (15)(16)(17)(18) and pre-frailty (19) . In Brazil, a study conducted in Porto Alegre/Rio Grande do Sul with 521 elderly (≥ 60 years) received in the Primary Health Care (PHC) network associated the condition of frailty with geriatric syndromes. The frequency of postural instability was 36.5%. There was an association between frailty and postural instability (p < 0.001) (20) .
The literature review showed a small number of studies investigating the association between physical frailty and postural instability, and the studies mostly focused on community-dwelling elderly and assisted by PHC. The present study focuses on outpatient care. As this is an unexplored context, the study may provide new subsidies for the implementation of nursing care.
The scientific evidence on the relationship between the variables of interest of the study, as contributory elements to physical vulnerability, is essential to direct and consolidate nursing care actions for frail elderly people.
In view of the above, the objective of the present study was to analyze the relationship between postural instability and the condition and markers of physical frailty in elderly patients in geriatrics and gerontology outpatient care.   (22) . In turn, the exclusion criteria, according to observation Before starting data collection, the team of examiners provided a two-day training session of 8 hours for the support group. The group was made up of undergraduate nursing students (undergraduate scholarship holders) and students from the research group. The training aimed to standardize the collections, the applications of the tests, and the way of approaching the elderly in the outpatient clinic. During the data collection, the team and support group were coordinated by the researcher, that is, by the main author of the present manuscript.

Method
A pilot study with ten elderly participants was carried out in order to check the adequacy of the instruments and make the necessary adaptations.
There was no need for changes. Thus, the ten elderly participants were included in the sample. Data The Mini Mental State Examination (MMSE) (22) was employed for cognitive screening. The total score varies from zero to thirty, with the following cutoff points being adopted: "13 points for illiterate elderly; 18 points for those with low and medium schooling (one to eight incomplete years of study); and 26 points for high schooling (eight or more years of study)" (23) . To evaluate gait speed (m/s), the elderly were instructed to walk a distance of 4.6 meters, usually on a flat surface. After adjusting for sex and height, the values in the lowest quintile were markers of frailty (3) .
Unintentional weight loss was checked through selfreport of the participants in response to two questions: (1) "Have you lost weight in recent months?"; (2) "How many pounds?" The participants who reported loss of body weight greater than or equal to 4.5 kg in the last twelve months were considered frail for this marker, in an unintentionally manner (without diet or exercise) (3) .
Fatigue/exhaustion was assessed through the self-report of the participants, according to the participant's response to items 7 and 20 of the Center for Epidemiological Scale -Depression (CES-D) (26)(27) , validated for community-dwelling Brazilian elderly (28) . Answers "2" or "3" for any of the questions indicated the elderly as frail for that marker (3) .
The Minnesota Leisure Activity Questionnaire (29) , validated for Brazilian elderly (30) , was used to assess level of physical activity. The questions relate to the frequency and time of activities carried out in the last year. The annual energy expenditure of each elderly person was calculated. After adjusting for sex, the values in the lowest quintile were considered indicators of frailty (3) .
Postural balance was evaluated through the Berg Balance Scale (BSE) (31) , translated and validated in Brazil (32) . This scale is aimed at frail elderly and evaluates

Results
The results showed a homogeneous sample in relation to the variables gender and age group. The The condition of frailty was associated with postural instability (p = 0.000) and pre-frailty (p < 0.001), and with the following markers of physical frailty: reduced hand grip strength (p = 0.0008), unintentional weight loss (p = 0.0094), reduced level of physical activity (p = 0.0001), fatigue/exhaustion (p < 0.0001) and reduced gait speed (p < 0.0001) ( Table 1). of the variability of the data and which was satisfactory to predict physical frailty associated to postural instability.

Discussion
The condition of physical pre-frailty was observed in more than half of the sample. In contrast with international (3,33) and national (34) studies, the values of frailty and pre-frailty found here were significantly higher. These investigations present different results from the present study, as they were conducted with community-dwelling elderly whose characteristics differ from those of elderly in the outpatient context.
International studies show great variability in the frequency of physical frailty, either in homogeneous or different populations of elderly people (35) . to 12% (3) .
Researchers point to socio-demographic and economic differences of developed countries to explain the variations in prevalence values of the syndrome (35) . Such variability is noticed boths in the conditions of physical frailty and also in its markers.
In eleven European countries (Sweden, Denmark, Germany, Netherlands, Belgium, Switzerland, Austria, France, Italy, Spain and Greece), frailty was present in 8.8% of the people aged over 50 years, and pre-frailty in 39.1% (33) . In turn, in South America (developing countries), the prevalence of frailty was reported to be 19.6% (36) and in Brazil 9.0%, according to data from the Frailty in Brazilian Elderly (FIBRA) study (34) .
In and decreased level of physical activity (14.2%) (11) . The domain of the markers was similar to that obtained in this study.

The frailty markers identified as most significant
in the sample (38) corroborate the results of the present study. There was a significant difference in the percentage of reduced level of physical activity.
Regarding postural instability, the value found in the present study was lower when compared to the percentages of international (39) and national (40)(41) studies.
In these studies we found a diversity of terms and concepts for the syndrome of postural instability, as well as disagreement between their results. dizziness is considered a geriatric syndrome due to its substantial prevalence, with a nonspecific and complex manifestation in the elderly population (40) .
Higher values were found in a population-based presented some health problem. Dizziness was the third major complaint; 48.3% of the participants reported feeling dizziness in the last month. The distribution among the elderly (≥ 60 years) was 34.8% (41) .
This variation of prevalence found between cities can be influenced by methodological biases such as the configuration of data collection, the description of the symptom, and the measure of prevalence used, with consequent increase of the values found.
In the present study, all markers of physical frailty were associated with postural instability: hand grip strength, unintentional weight loss, physical activity, fatigue/exhaustion, and gait speed. Furthermore, there was an association between postural instability and the conditions of pre-frailty and frailty.
Regarding the statistical association between postural instability and frailty, studies conducted in the USA (19) , France (18) and even in Brazil (20,43) reinforce the results of the present study. In the community of to 1.20) (19) .
In this sense, researchers in Troyes/Champagne There was association between postural instability and frailty (p < 0.001) (20) .
In order to evaluate the balance and classify the elderly as frail, non-frail and pre-frail, an intervention study developed in the city of Ribeirão Preto/São Paulo (Brazil) investigated 60 elderly individuals (≥ 65 years).
Balance was evaluated by the BESTest and with a force platform. The result of such study were in line with those of the present study, pointing out that balance is lower in frail elderly 14.2% (n = 60) when compared to the non-frail ones (p = 0.0001) (44) .
It is emphasized that postural instability in elderly patients is worrisome due to the consequences of this clinical characteristic, which are falls. In Goiânia/Goiás The researchers concluded that balance is a protective factor against falls (49) . and women (OR = 17.4; 95% CI: 11.8-23.0) (50) .
The predominance of reduced level of physical activity and the association with the physical frailty of the elderly reinforces the recognition that this parameter is an important marker of frailty. It is important to emphasize that the nursing professionals should encourage the elderly to daily physical activity, because its benefits in the aging process are a consensus in the current literature (51) .  (53) . These results are similar to the present study, although divergent in the marker reduced level of physical activity.
Managing physical frailty (2)  The results of the present study bring significant contributions to gerontological practice and reinforce the need for nursing to create effective opportunities for older people to engage with physical activity practices.